Computes the sphere that encloses the axis-aligned bounding box
(AABB) of the given vertices, using the same convention as rgl's
Sphere(AABB) auto-framing (see rgl src/geom.cpp) and scimesh's
camera_auto(rgl_compat=TRUE): the center is the AABB center and the
radius is half the length of the AABB diagonal.
bounding_sphere(vertices)a list with entries center (numeric vector of length 3) and
radius (numeric scalar). For an empty/zero-extent input, radius
is 0 and the center is the single vertex (or NA if no vertices).
an Nx3 numeric matrix of vertex coordinates, or a
mesh3d/tmesh3d object, or an fs.surface, or a list of
any of these (all vertices are pooled).